It feels like most of your position comes from a place of misunderstanding just what goes into a lesson plan about literature; possibly even a deliberate misunderstanding. Schools aren’t giving children books with smut and senseless violence. These materials are constantly being reconsidered and reevaluated. Vonnegut was something taught when I was in school, and removed right after I graduated.
This comic is pointing at the fact that nearly every book on these lists isn’t there because the content is actually a problem. The lists just have books that some religious group dislikes regardless of whether or not they’re being used.
Besides, somehow the christian Bible is somehow still “approved” while having more rape and violence and men kissing men than any book I ever had to read for school.